94.5% of residents of Casper speak English at home.
3.3% of residents speak Spanish at home (76% speak English very well, 13% speak English well, 9% speak English not well, 2% don't speak English at all).
1.4% of residents speak other Indo-European language at home (76% speak English very well, 15% speak English well, 9% speak English not well).
0.3% of residents speak Asian or Pacific Island language at home (68% speak English very well, 19% speak English well, 13% speak English not well).
0.5% of residents speak other language at home (78% speak English very well, 12% speak English well, 10% speak English not well).

Foreign born population: 997 (2.0%)
(48.2% of them are naturalized citizens)